CO Laser-Stabilized Ni-Co Dual Single-Atomic Sites for Energy Generation and Ammonia Harvesting.

Dual single-atom catalysts (DSACs) hold immense potential in electrochemical nitrate (NO ) reduction (EcNR) as a sustainable replacement to the Haber-Bosch process for the production of ammonia (NH). However, challenges such as synthesis complexity, low purity, scalability, and stability have hindered their practical application. Herein, a rapid and scalable method is introduced to stabilize low-cost 3d transition metals (Ni and Co) as DSACs on TiCT MXene in 10 min using continuous-wave CO-laser irradiation. Ni and Co ions are chelated and stabilized as single atoms onto an L-tryptophan-modified TiCT surface via metal─O and metal─N bonds, forming Ni-single atom catalyst (SAC)/MXene, Co-SAC/MXene, and NiCo-DSAC/MXene. This approach enhances MXene properties, enabling the synthesis of efficient atomic-level electrocatalysts. Potential-resolved in situ Raman spectroelectrochemistry and density functional theory reveal that EcNR proceeds through NO reduction to NO, NO, NH, and NH intermediates, ultimately forming NH via final protonation step. This process exhibits a low limiting potential of -0.37 V, with NO protonation identified as the critical step. NiCo-DSAC/MXene exhibited superior EcNR performance for NH production in 1.0 M potassium hydroxide with sustained multiple cyclic stability. Furthermore, this catalyst is integrated into a Zn-NO a battery that simultaneously removes NO , generates energy, and synthesizes NH.